1. Field of the Invention
The present invention relates to an earthquake precursor observing device, a method thereof, and an earthquake precursor observing program for observing an earthquake precursor based on earthquake data obtained from a weak earthquake.
2. Description of the Related Technique
Currently, an earthquake precursor prediction instant alert system has already been developed for informing the estimated intensity and estimated arrival time of an earthquake and for supporting prompt preparation for the earthquake to prevent having damages of disasters (Japanese Unexamined Patent Publication 2003-66152: Patent Document 1).
The earthquake prediction instant alert system according to Patent Document 1 is an earthquake prediction instant alert system which predicts and alerts the arrival time of an seismic wave based on realtime information regarding the earthquake, which includes: a receiving module for receiving the realtime information regarding the earthquake; a first judging module for judging necessity of dispatching an alert based on the realtime information received by the receiving module; a prediction calculation module for calculating a prediction of the seismic wave arriving at a specific location based on the realtime information received by the receiving module; and an alert module which alerts the arrival of the seismic wave prediction-calculated by the prediction calculation module. The earthquake precursor observing device transmits an earthquake parameter determined by a network of seismic stations before the seismic wave arrives at the location, and instantly calculates and displays necessary information for that location by considering the position of that location and the seismologic characteristic.
The earthquake prediction instant alert system according to Patent Document 1 may be useful for informing the estimated intensity and estimated arrival time of an earthquake and for supporting prompt preparation for the earthquake to prevent having damages of disasters. However, the system alerts the estimated intensity and the estimated arrival time of an earthquake based on the realtime information regarding the earthquake, so that it is necessary to prepare for the occurrence of an earthquake in units of several minutes.
It is therefore an exemplary object of the present invention to provide an earthquake precursor observing device, a method thereof, and an earthquake precursor observing program for observing a precursor of an earthquake by finding an active fault which induces an earthquake based on seismic waves received at observation points.
In order to achieve the foregoing object, the earthquake precursor observing device according to the present invention is an earthquake precursor observing device for observing an earthquake precursor based on actually measured earthquake data, which is characterized to include: a data acquisition module which acquires earthquake data actually measured at a plurality of observation points; a pulse calculation module which acquires information of a propagation environment where seismic waves propagate from a hypocenter of an earthquake to each of the observation points, and applies time reversal processing on the seismic waves received at the plurality of observation points by considering the propagation environment to acquire time reversal pulses at each of the observation points; a line calculation module which calculates a parametric line in a length direction of a fault from a distribution of azimuths of frequency spectra of the time reversal pulses acquired by the pulse calculation module; a head searching module which searches a parametric head by analyzing the seismic waves received in the vicinity of the parametric line calculated by the line calculation module; and a monitoring module which monitors developments of a crack in the fault by observing the parametric head searched by the head searching module.
The earthquake precursor observing method according to the present invention is an earthquake precursor observing method for observing an earthquake precursor based on actually measured earthquake data, and the method is structured to include: acquiring earthquake data actually measured at a plurality of observation points; acquiring information of a propagation environment where seismic waves propagate from a hypocenter of an earthquake to each of the observation points; acquiring time reversal pulses at each of the observation points by applying time reversal processing on seismic waves received at the plurality of observation points by considering the propagation environment; and calculating a parametric line in a length direction of a fault from a distribution of azimuths of frequency spectra of the time reversal pulses acquired; searching a parametric head by analyzing the seismic waves received in the vicinity of the calculated parametric line; and monitoring developments of a crack in the fault by observing the searched parametric head.
The earthquake precursor observing program according to the present invention is an earthquake precursor observing program for observing an earthquake precursor based on actually measured earthquake data, which is structured to cause a computer to build: a data acquisition module which acquires earthquake data actually measured at a plurality of observation points; a pulse calculation module which acquires information of a propagation environment where seismic waves propagate from a hypocenter of an earthquake to each of the observation points, and applies time reversal processing on the seismic waves received at the plurality of observation points by considering the propagation environment to acquire time reversal pulses at each of the observation points; a line calculation module which calculates a parametric line in a length direction of a fault from a distribution of azimuths of frequency spectra of the time reversal pulses acquired by the pulse calculation module; a head searching module which searches a parametric head by analyzing the seismic waves received in the vicinity of the parametric line calculated by the line calculation module; and a monitoring module which monitors developments of a crack in the fault by observing the parametric head searched by the head searching module.
As described above, the present invention can provide such an effect that it is possible to monitor developments of an active fault in addition to the existence of the active fault and the azimuth characteristics thereof based on the actually measured earthquake data, so that precursor of earthquakes can be monitored accurately.